The Canary Islands lie off the southwest coast of Spain. Though Castilian Spanish is the official language of the island chain, some adults on the island of La Gomera still use Silbo Gomero, an ancient language that’s “spoken” through whistles. In fact, Silbo (taken from the Spanish word silbar, “to whistle”) boasts a vocabulary of more than 4000 words that can be heard from miles away, which is useful considering the island’s rugged, hilly terrain. With only four vowels and four consonants, the key to understanding Silbo is understanding the nuances and meanings of the various tones of whistles.

According to Sarah Andrews, Silbo was most likely first used as an emergency signal, but over time, it developed into a full language. Over the years, of course, the language all but disappeared, but recently, it’s made a comeback. In fact, the government is trying to resurrect the whistling language by teaching it in schools.